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Jonathon Porritt: 'I am not going to run away and be a hippy'

This week, after nine years of leading the Sustainable Development Commission, Jonathon Porritt left his post. So what now for Green party member and Treasury antagonist who was brought into government as a 'critical friend'?

When Jonathon Porritt – official government green adviser – this week left his Whitehall office after nine years trying to crash the gears of the machine of state, his staff of 60 in the Sustainable Development Commission (SDC) didn't just say cheerio; they hired an old ship on the Thames, formed a blues band and sang him out to a Muddy Waters tune:

For nine long years this green guru reigned

Watching over Whitehall, his eye keenly trained

Tree-hugger-in-chief or simply JP

However you know him you should start to see

He's a true ninja of sustainability

Porritt stood to one side of the crooning SDC backing singers, delighted but emotional at his send off. But he probably didn't feel much like a ninja of anything – he was still shaken after a black-cab driver had almost killed him as he was cycling to Channel 4.

Six days later, the most influential green thinker of his generation – a man who as one-time director of Friends of the Earth has advised everyone from Prince Charles to Tony Blair – was hobbling around on crutches; this time, the result of falling off his bike after swerving to avoid a Mercedes' door opened in his path. Two near-fatal accidents in a week suggests a man who either bikes like a lunatic or relishes danger. Neither, he insists, are true. But he is certainly a brave man, as his nine-year stint as a signed-up Green party member at the heart of Whitehall demonstrates. He admits that he did sometimes despair at the scale of the change needed to turn government round.

Black marks from the old Etonian, former grammar school teacher first: the Treasury, and the departments of business and transport have been by far the worst at integrating environment, economy and social matters, he says. "The tragedy is that if these departments had been brought aboard, then it would have been a different story. But Transport is really, seriously unreconstructed, the worst department of all. It's incomprehensibly, devastatingly bad. It has been quite horrible for government. Blair never went after it. Mondeo man still looms large there.

"And now that [Lord] Adonis has come in as transport secretary, I have been rocking in the aisles. Here's this guy who civil servants send to Holland – a country where cycling and walking are a way of life – and he comes back and says 'we can do this'. Good grief!"

Civil servants next: Porritt says working in Whitehall after years in business and non-governmental organisation groups such as Friends of the Earth and Forum for the Future has been a real shocker. "It's called path dependency. You get locked in. When you have a group of very senior power brokers they only do things one way. Civil servant attitudes are a real brake on change. 'We have our view,' they say, 'and if nothing happens, well, too bad.' If the UK fails to reach its emission targets it won't be due to technological failure but this."

Ministers have alternately appalled and impressed him. Housing chief John Healy is "blind to sustainable development", he says, and another minister who he won't name publicly is "an arrogant little shit". But top ninja marks go to Ed Miliband ("a real star, he's done more in six months than everyone in the three years before"), Michael Meacher ("a kindred spirit but it's always a mixed blessing having Michael as your ally") and Gordon Brown.

"Climate change was always Tony Blair's thing. It was never Gordon's natural tendency. Gordon had spent time curling his lip at it saying, 'I do more serious things like Africa'. But over time he has got stronger and stronger. He's grown. And his commitment to Dfid's [Department for International Development] budget has been remarkable. What other country in these times would maintain its overseas aid and propose £100bn for climate change?"

Porritt is 59. The hair is going, the body is temporarily crocked but his years as a renegade civil servant have only fuelled the green radicalism. He still thinks Labour was mad to get him of all people to work inside the system. "Meacher persuaded John Prescott to set it [the SDC] up. Yet Prescott could never understand why a government body would beat up government. He went apoplectic with us one time. He literally screamed and stamped round the room kicking things. I have never had a meeting with him since."

When Porritt started, the SDC was a titchy £350,000-a-year operation with an unique licence to be independent, provoke, criticise and scrutinise government as a "critical friend". But it has grown into the government's most authoritative and provocative quango and has challenged it on everything from climate to roads, equality, housing, economics, consumption, and health.

"Setting up the SDC was a very brave thing to do. No other western government has a body like this. When we started we had no relationships with any department, we reported to the prime minister but we had no access to senior government. It took three years to get anywhere. Our ambition was to make it really authoritative, and get top-notch people inside government. We've done that. We have greatly increased the level of confidence within government of dealing with sustainable development."

It has also made it some powerful enemies. Recently the SDC argued that consumer-driven economic growth could not possibly be sustainable. This was heresy, especially in the Treasury. "The [report] was deeply unloved in government. Yet our entire economic system is based on growth. The only thing they want is to get people to go out there and consume as much as possible."

But SDC's best work may be invisible. "The watchdog role, especially, has been impossible for government to ignore. Whitehall is a heaving bureaucracy and you make it work for you," he says, "only by making its systems friendly to sustainable development." So they learned Whitehall street fighting, smuggling words into documents and forcing permanent secretaries to set sustainable development performance targets, making the machine work for them. "It sounds geeky but it's the nitty-gritty boring bits that count," he says.

And he retains a special, venomous relationship with his old foes like the nuclear industry: "Little more than a year ago, these nuclear zealots were telling the world that any new nuclear in the UK would require zero public subsidies. Hardened anti-nuclear campaigners such as myself fell about laughing – not one kilowatt-hour of nuclear-generated electricity has ever gone on to the grid, anywhere in the world, over 40 years, without some kind of public subsidy. So why does anybody suppose that it's going to be any different this time round?

"We [in the SDC] said categorically that there was no way the industry could build new stations without subsidies. Government said we were wrong, explicitly. All the energy companies, too said they did not need subsidies. Now, they are all in there asking for large amounts of public money.

"No one in government will now talk to us about nuclear," he says.

He is entitled to claim a baronetcy and be known as the Hon Sir Jonathon Porritt, 2nd Baronet – dad was governor of New Zealand and, as it happens, a 1924 bronze-winning Olympic athlete in the Chariots of Fire 100m race. But he always refuses to take the title, perhaps holding out to be elected one day into the Lords. So where now for the ninja who was born into the British establishment but who has spent a working life challenging it? "I am not going to run away and be a hippy. I will continue to work with Forum for the Future [which he set up with fellow green campaigner Sara Parkin] but now I will have time to get involved in campaigning again."

Climate change activists can expect a new ally. "Environmental campaigners just do not understand how their rights have been eroded in the name of security or terrorism. I will also help Caroline Lucas in Brighton. She's an astonishing, genuinely electable politician. But I am not going to take a big role in the Green party or stand for parliament. I don't want to be caught up in the internecine complexities of party politics," he says.

He leaves government with genuine hope. "Two great things have happened. The business community is now largely aboard. And we also now have a civil society capable of driving change – NGOs but also countless other organisations, like the WI and the Rotary, that play huge parts in our lives. NGOs are sniffy but these groups are fundamental to what makes society tick. They are now on board. They all know that consumption-based economic growth is mad. If the government – any government – gets its head round the potential of their power, then real change is possible."